Spin bath arrangement



3 M .Fm 1H M 8 WV 1 m z m April 14, 1959 Filed Aug. 28. 1953' E J GRISET, JR

SPIN BATH ARRANGEMENT A TTORNEY United States Patent SPIN BATH ARRANGEMENT Application August 28, 1953, Serial No. 377,127

1 Claim. (Cl. 18-8) This invention relates to the production of thread and more particularly to a spin bath arrangement used in a wet spinning process.

In the production of artificial threads by wet spinning it is common practice to arrange a plurality of spinnerets or jets along a spinning trough filled with a coagulating liquid. In the process of extruding the thread forming solution through the spinnerets to form threads, the coagulating solution or so-called spin bath becomes depleted in strength and contaminated with impurities. It is therefore necessary to withdraw the weakened spin bath from the trough for the purpose of replenishing its strength and removing impurities. This is generally done on a continuous basis with spent solution being removed from the trough while fresh solution is being supplied to the trough.

It is recognized in the art that it is highly desirable to maintain a uniform concentration of acid at the several spinnerets disposed along the spin bath trough. In the absence of such uniformity, variations in physical properties of the thread occur from one point to another along the trough. To obtain uniformity, attempts have been made to increase the rate at which the spin bath is supplied to and withdrawn from the trough to minimize the change in concentration of the spin bath in the trough. However, these attempts to increase the flow rate of spin bath have resulted in additional difficulties in the formation of eddies or currents due to the fast flowing liquid. Such eddies or currents tend to create irregularities and disturbing influences in the spinning process. In addition, the circulation of large volumes of liquid at high rates of flow increases the expense of manufacturing the yarn.

It is an object of the present invention to improve the point-to-point uniformity in a wet spinning process.

It is another object of the present invention to provide an apparatus for supplying spinning solution in a Wet spinning process.

A further object of the invention is to provide an apparatus for supplying acid spin bath to freshly extruded viscose solution.

A still further object of the invention is to provide an apparatus for supplying acid spin bath in a uniform concentration and at a uniform rate to a plurality of spinnerets disposed along a spinning machine.

Other objects will appear from the following detailed description taken in conjunction with the annexed drawings wherein:

Figure 1 is a plan view of a portion of a spinning machine modified in accordance with the present invention; and

Figure 2 is a sectional elevation taken along the line 2-2 in Figure 1.

In accordance with the present invention a uniform flow of spin bath is obtained at each spinning point by positioning each spinneret in the spin bath trough in the path of liquid flowing between a liquid inlet point and a liquid withdrawal point. Not more than one spinneret is placed in each such liquid path. Preferably each spinneret is located in a vertical plane that intersects a point at which liquid is supplied to the spin bath and a point at which liquid is withdrawn from the spin bath.

The drawings illustrate the practice of the present invention in a viscose rayon spinning process. It will be apparent that the invention may also be used with other types of wet spinning processes. I Referring now to the drawings, there is shown a rectangular shaped open top trough 10 which runs the entire length of a viscose rayon spinning machine (not shown). Trough 10 is provided with a back wall 11, a front wall 12 and a bottom 13, each constructed of an acid resistant substance such as lead.

Trough 10 is substantially filled with a coagulating or acid spin bath 14. Trough 10 is supported by frame 15. The spin bath 14 is constantly supplied to trough 10 fromspaced acid supply or inlet conduits 16,-17, 18, 19, etc., aligned in a row extending longitudinally of the trough adjacent back wall 11. Conduit 16-19, inclusive, are each connected to an acid supply header 20 disposed on the bottom 13 of trough 10 and extending the length of trough 10 underneath conduits 16-19, inclsive. It will be seen from Figure Z that the acid leaving header 20 first rises up inside a conduit 21 which is concentrically surrounded by the acid supply conduit 16. A cap 22 surrounds the top of acid conduit 16 so as to cause the acid reaching the top of inner conduit 21 to flow back down through the annular space outside conduit 21 before it is admitted to spin bath 14. Conduits 17-19 are constructed similar to conduit 16 as shown in Figure 2.

Spin bath is constantly withdrawn from trough 10 to acid removal header 23 through a number of spaced vertical overflow pipes or outlet conduits 24, 25, 26, 27 28, etc., aligned in a row also extending longitudinally of trough 10. It will be noted that vertical overflow pipes 24-28, inclusive, are disposed adjacent front wall 12 of trough 10 and staggered with respect to corresponding inlet conduits in such a manner that a typical inlet conduit 17, for example, will supply coagulating bath to a pair 25, 26 of outlet conduits adjacent thereto. Moreover, a typical outlet conduit 25, for example, will receive flowing coagulating bath from both adjacent inlet conduits 16, 17, all as can be seen upon inspection of Figure 1.

Extending the length of the spinning machine parallel to trough 10 is gutter 29 which may be used to carry away waste which accumulates during spinning operations, etc. Pivotally mounted in the usual manner at spaced intervals above gutter 29 are a plurality of candle filter assemblies 30, 31, 32, 33, 34, 35, 36 and 37. The pivotal mounting permits easy removal of the spinnerets from the bath 14 for changing or cleaning. A spinning solution supply header (not shown) supplies viscose solution to filters 30-37, inclusive. Attached to filters 30-37, inclusive, are spinning solution supply lines 38-45, inclusive, respectively. Supply lines 38-45, inclusive, supply viscose solution to spinnerets 46-53, inclusive, respectively.

It will be noted that when the spinnerets are submerged in the spin bath 14 as shown in the drawings each spinneret is disposed approximately midway along a horizontal line between the axis of an acid supply conduit and an overflow pipe. It will be further noted that the face of spinneret 48 is disposed in the baths 14 at a depth slightly above the horizontal plane at which fresh acid enters spin bath 14 from conduit 16.

It is preferred that the face of each spinneret be disposed in a horizontal plane not below the point at which fresh acid enters spin bath 14. However, this position may be varied slightly depending on the configuration of the acid supply conduit 16 and the pressure under which acid is delivered through header 20, the objective being to placethe face of the spinneret in the path of acid flow between the acidsupply conduit inlet and the overflow pipe outlet.

It has been found that pronounced improvements are obtained-by using the spin bath arrangement of the present invention in the production of viscose rayon. For examplepin a-spin bath arrangement previously used, distinct variations in certain physical properties of viscose rayon thread occurred from one point to another along the :spin bath trough. Variations in denier, elongation, fatigie and dyeing properties were especially noticeable among packages of thread collected at different points along the same spinning machine. By the use of the present invention it has been found that such variations are greatly minimized or altogether eliminated. Furthermore, the present invention permits a reduction in the rate of acid flow per point without incurring the non-uniformity usually accompanying such reduced flow rate.

The acid circulation scheme of the present invention maybe easily installed on conventional spinning equipment at moderate expense. While a preferred embodimentof the invention has been described above, it will be apparent that various modifications may be made without departing-from the spirit of the invention.

What is claimed is:

A spin bath arrangement for the production of threads comprising an elongated trough containing a coagulating bath maintained at a fixed level, a plurality of spaced inlet conduits aligned in a row extending longitudinally of said trough below the level of said coagulating bath, a plurality of spaced outlet conduits corresponding in number to said inlet conduits and aligned in a row also extending longitudinally of said trough, said outlet conduits being staggered with respect to corresponding inlet conduits, means for supplying coagulating bath through each inlet conduit and for Withdrawing coagulating bath from each outlet conduit, the staggered relationship of said inlet and outlet conduits establishing a stream of coagulating bath flowing from each of said inlet conduits to a pair of outlet conduits adjacent thereto and toeach outlet conduit from two adjacent inlet conduits, and a plurality of spaced spinnerets aligned in a row extending longitudinally of said trough, each spinneret being disposed in vertical and horizontal alignment with one stream of coagulating bath flowing from one inlet conduit to a corresponding one of said outlet conduits, whereby a uniform concentration of coagulating bath will be supplied at a uniformrate to each in a pair 'of spinnerets by a single inlet conduit.

References Cited in the file of this patent UNITED STATES PATENTS 2,611,928 Merion et al Sept. 30, 1952 

